Bowling and certain other sports, for example, softball pitching, horseshoes, lawn bowling, bocce ball, curling, and others require the participation to use an underhand throwing motion.
In addition to this throwing motion, for a right-handed participant, several other motions or positions are common for proper and consistent form. The left foot is pointed at the target at delivery; the left knee is bent; there is a forward bend at the waist; the right leg is extended for balance as is the left arm; and the arm swings through delivery like a pendulum. Also, at the same time, the right arm bends at the elbow in the follow-through; the right wrist, hand, thumb, and fingers all break upwardly in sequence; and the head, eyes, and shoulders are square, i.e. facing the target. As is the case with most sports or games, the more one practices, the better one becomes. Extensive practice can change amateur players into professionals. However, practice requires effort, time, a practice facility, and can be quite expensive.
Practice devices for many different sports are known in the prior art. U.S. Pat. Nos. 3,341,208 and 4,071,251 teach golf swing training aids. U.S. Pat. No. 4,220,333 to Mercer shows a bowling practice device in which a conventional bowling ball is retained within a cage-like retainer structure secured to the participant's wrist. As the bowler practices, the ball is released into the retainer, obviating the need for the bowler to practice at a bowling facility.
With particular regard to the sport of bowling, success depends to a large part on the proper release of the ball at the foul line. Most current professional bowlers release the ball and finish the stroke in the same basic manner. As the ball is released, the thumb comes out of the ball first, allowing the fingers and wrist to guide the rotation of the ball. As the arm continues into the follow-through, the thumb ends up pointing toward the eyes of the bowler. In addition, the head remains straight, eye contact is focused on a spot over which the ball is released, the shoulders are square to the target, the knees are bent, and the lead foot is pointed straight toward the head pin. These mechanics can be practiced virtually anywhere but currently are best practiced at bowling lanes. Unfortunately, time constraints, lane availability, costs, and other factors combine to limit practice time and consequently, improvement.